Ti–O–Cu Nanotubular Mixed Oxide Grown on a TiCu Alloy as an Efficient Material for Simultaneous Photoelectrocatalytic Oxidation and PMS Activation for Pollutant Degradation

This study introduces a novel photoelectrocatalytic (PEC) system featuring a Ti-O-Cu mixed nanotubular oxide photoanode for the simultaneous activation of peroxymonosulfate (PMS), targeting the removal of emerging contaminants, such as methylene blue dye, tetracycline, and ibuprofen. The Ti-5.5Cu (atom %) alloy substrate and the nanotubular oxide layer were synthesized through arc melting and electrochemical anodization. The conditions of photoelectrocatalysis-assisted PMS activation (PEC/aPMS) were optimized using experimental design, achieving 90.4% decolorization of methylene blue dye within 30 min under optimal conditions: pH 4, an applied potential of 0.5 V vs Ag/AgCl, and a PMS concentration 50 times the molar concentration of the contaminant, utilizing a 10 W UV LED at 365 nm. In contrast, only 25% decolorization was observed without PMS. Singlet oxygen (¹O₂) was identified as the primary pathway for PMS activation (nonradical). Additionally, the PEC/aPMS system effectively degraded model contaminants, achieving 52% degradation of ibuprofen, 78% of methylene blue, and 92% of tetracycline in 10 mg L^-1 total organic carbon solutions within 60 min under optimized conditions. The electrode exhibited remarkable stability, maintaining its efficiency throughout the experiments. These findings highlight the potential of mixed nanostructured oxide electrodes for developing highly efficient and durable PEC systems with integrated PMS activation for the removal of organic contaminants.